Affect Heart Rate Variability Research Articles

Feet-heating and calf-heating have opposing effects on glucose tolerance and heart rate variability: a randomized, controlled, crossover trial.

Heat exposure's effect on glucose tolerance depends on the amount of body exposed, likely relating to autonomic nervous system balance. We assessed how partial-body heat exposure at two different levels of the lower extremities affects glucose tolerance and autonomic nervous system balance, measured via heart rate variability. We hypothesized feet-heating would improve glucose tolerance without affecting heart rate variability, while calf-heating would worsen glucose tolerance and decrease heart rate variability compared to a thermoneutral control condition. In a randomized, controlled, crossover trial, healthy participants' (N=31, 23(3) years, 45% male) glucose tolerance was measured in (A) thermoneutral; (B) feet-heating; and (C) calf-heating conditions. Every 30 min for 2 h, blood glucose, heart rate, heart rate variability, tympanic temperature, thermal comfort scores, and blood pressure were measured. There were significant interactions between condition and time for blood glucose (F (4.6,72.6)=2.6, p=0.036), heart rate (F (3.4, 54.5)=3.5, p=0.017), heart rate variability (F (4.3,63.2)=7.5, p<.0001), tympanic temperature (F (8, 268)=2.4, p=0.014), and thermal comfort scores (F (8, 248)=22.1, p<0.0001). Calf-heating increased 90 min glucose (+12 (95% confidence interval, CI: 3-21) mg/dL, p=0.013) and decreased heart rate variability throughout (mean decrease: 13%-22%, p<0.007), while feet-heating lowered 90 min glucose (-7 (95% CI: -16 to+1) mg/dL, p=0.090) without affecting heart rate variability (p=0.14-0.99). Blood pressure and body temperature were similar between conditions, but heart rate and thermal comfort scores increased with heating. Calf-heating worsens, while feet-heating may improve, glucose tolerance. Changes in heart rate variability coincided with changes in glucose tolerance despite unchanged body temperature. Whether heart rate variability can be used to monitor autonomic nervous system balance during heating to optimize its acute effect on glycemic indices should be further explored.

Predicting Sleep Quality through Biofeedback: A Machine Learning Approach Using Heart Rate Variability and Skin Temperature.

Sleep quality (SQ) is a crucial aspect of overall health. Poor sleep quality may cause cognitive impairment, mood disturbances, and an increased risk of chronic diseases. Therefore, assessing sleep quality helps identify individuals at risk and develop effective interventions. SQ has been demonstrated to affect heart rate variability (HRV) and skin temperature even during wakefulness. In this perspective, using wearables and contactless technologies to continuously monitor HR and skin temperature is highly suited for assessing objective SQ. However, studies modeling the relationship linking HRV and skin temperature metrics evaluated during wakefulness to predict SQ are lacking. This study aims to develop machine learning models based on HRV and skin temperature that estimate SQ as assessed by the Pittsburgh Sleep Quality Index (PSQI). HRV was measured with a wearable sensor, and facial skin temperature was measured by infrared thermal imaging. Classification models based on unimodal and multimodal HRV and skin temperature were developed. A Support Vector Machine applied to multimodal HRV and skin temperature delivered the best classification accuracy, 83.4%. This study can pave the way for the employment of wearable and contactless technologies to monitor SQ for ergonomic applications. The proposed method significantly advances the field by achieving a higher classification accuracy than existing state-of-the-art methods. Our multimodal approach leverages the synergistic effects of HRV and skin temperature metrics, thus providing a more comprehensive assessment of SQ. Quantitative performance indicators, such as the 83.4% classification accuracy, underscore the robustness and potential of our method in accurately predicting sleep quality using non-intrusive measurements taken during wakefulness.

Effect of psychosocial factors on autonomic nervous system activity in patients with heart failure.

Autonomic imbalance predicts worse clinical outcomes in patients with heart failure (HF). Managing the variables affecting heart rate variability (HRV) might improve the clinical outcomes of patients with HF. This study aimed to investigate variables affecting HRV. We assessed autonomic nervous system activity (low-frequency [Lf], high-frequency [Hf], and Lf/Hf ratio) in 60 patients with HF, employing standard measures to capture short-term HRV. To estimate the independent effects of variables such as well-known cardiac risk factors and psychosocial conditions on HRV, multivariate analyses were conducted. For psychosocial variables, we assessed depression and quality of life in patients and their family caregivers. We also assessed the self-care behavior of patients and their caregivers' burden. Depression in family caregivers and self-care behavior of patients were independently associated with a decreased Hf (β-coefficient = 0.309, P = .039 and β-coefficient = -0.029, P = .047, respectively). Depression of family caregivers and self-care behavior of patients may affect HRV in patients with HF.

Analysis of HAM-D Scores on Cognitive Functions and Heart Rate Variability in Patients with Major Depressive Disorder.

Previous research has shown that Major Depressive Disorder (MDD) is accompanied by severe impairments in cognitive and autonomic processes, which may linger even when mood symptoms recover. This study aimed to analyse the relationship between depression severity, as measured by the Hamilton Depression Rating Scale (HAM-D), and how it affects heart rate variability (HRV) and cognitive function in patients with Major Depressive Disorder (MDD). The cross-sectional study was conducted at RUHS College of Medical Sciences and Associated Hospitals, Jaipur, from July 2022 to January 2023 on 90 subjects having major depressive disorder (MDD) of either sex in the 20-40 age group using the Hamilton score for depression (HAM D), Heart Rate Variability (HRV) measurements, and a battery of cognitive tests. Regression analyses were conducted to examine the associations between HAM-D scores with both HRV parameters and cognitive functions. Results indicated a significant negative correlation between HAM-D scores and HRV measures with p<0.001, suggesting that increased depression severity is associated with reduced HRV. Additionally, higher HAM-D scores predicted poorer performance on cognitive tasks, particularly in the domains of executive function and working memory. The coefficient of determination r2=0.724 suggests that approximately 72.4% of the variance in the dependent variable (Hamilton rating score for depression) could be explained by the combined cognitive function and heart rate variability parameters. These findings highlight the potential utility of, emphasizing the importance of comprehensive assessment and treatment approaches that address both the affective and cognitive aspects of depression.

Brain connectivity networks underlying resting heart rate variability in acute ischemic stroke

Acute strokes can affect heart rate variability (HRV), the mechanisms how are not well understood. We included 42 acute stroke patients (2–7 days after ischemic stroke, mean age 66 years, 16 women). For analysis of HRV, 20 matched controls (mean age 60.7, 10 women) were recruited. HRV was assessed at rest, in a supine position and individual breathing rhythmus for 5 min. The coefficient of variation (VC), the root mean square of successive differences (RMSSD), the powers of low (LF, 0.04–0.14 Hz) and high (HF, 0.15–0.50 Hz) frequency bands were extracted. HRV parameters were z-transformed related to age- and sex-matched normal subjects. Z-values < -1 indicate reduced HRV. Acute stroke lesions were marked on diffusion-weighted images employing MRIcroN and co-registered to a T1-weighted structural volume-dataset. Using independent component analysis (ICA), stroke lesions were related to HRV. Subsequently, we used the ICA-derived lesion pattern as a seed and estimated the connectivity between these brain regions and seven common functional networks, which were obtained from 50 age-matched healthy subjects (mean age 68.9, 27 women). Especially, LF and VC were frequently reduced in patients. ICA revealed one covarying lesion pattern for LF and one similar for VC, predominantly affecting the right hemisphere. Activity in brain areas corresponding to these lesions mainly impact on limbic (r = 0.55 ± 0.08) and salience ventral attention networks (0.61 ± 0.10) in the group with reduced LF power (z-score < -1), but on control and default mode networks in the group with physiological LF power (z-score > -1). No different connectivity could be found for the respective VC groups. Our results suggest that HRV alteration after acute stroke might be due to affecting resting-state brain networks.

Heat illness detection with heart rate variability analysis and anomaly detection algorithm

Objective:Incidence of heat illness has been increasing dramatically due to the progression of global warming. Preventing severe heat illness, called heatstroke, is crucial because it can lead to long-term multiple organ damage, including the brain, and results in more than 600 deaths per year in the United States. It has been reported that heat stress affects heart rate variability (HRV), which is the fluctuations of the R-R interval (RRI) on an electrocardiogram (ECG). We propose a method for detecting symptoms of heat illness based on HRV analysis in order to prevent exacerbation of heat illness. Methods:In the proposed method, monitoring abnormal changes in HRV caused by heat stress is monitored. Multivariate statistical process control (MSPC), a commonly used anomaly detection method in machine learning, is adopted for training the heat illness detection method. To validate the proposed method, we recruited 103 healthy volunteers with risks of heat illness development: employees working in hot environments, athletes, and amateur marathon runners. Data collection was performed using our wearable heart rate sensor and smartphone app. Results:The result of applying the proposed method showed that a sensitivity of 75% (21 out of 28 cases) and a false-positive rate of 1.02 times per hour were achieved. Conclusion:The proposed heat illness detection method will be used in daily life because RRI data can be easily measured by a wearable sensor. Significance:The proposed method will contribute to receiving appropriate treatment for heat illness before exacerbation, which contributes to protecting people’s health.

How Do Qualities of Supportive Conversations Affect Heart Rate Variability During Conversations About the Death of a Parent?

ABSTRACT This study examined the impact of person-centered communication on bereaved young adults’ physiological stress responses when they talked about the death of their parent. Heart rate variability – indexed by the standard deviation of the normal-to-normal intervals (SDNN), the root mean square of successive differences (rMSSD), and the heart rate variability index (HRVi) – was monitored before, during, and after the interaction as an objective measure of stress reactivity and recovery. The final sample included 69 subjects, and they conversed with research confederates who provided varying levels of person-centered support. The results showed that participants who received highly person-centered support experienced faster stress recovery, as indicated by increased HRVi, compared to those who received moderately or low person-centered support. Bereaved adults’ SDNN during the interaction was positively associated with subjective evaluations of cognitive reappraisal, emotional improvement, and support quality. The discussion highlights the significance of supportive interactions on physiological, psychological, and emotional well-being.

The Influence ofPhysical andMental Health Mediators onthe Relationship Between Combat-Related Traumatic Injury andUltra-Short-Term Heart Rate Variability ina U.K. Military Cohort: A Structural EquationModeling Approach.

Combat-related traumatic injury (CRTI) adversely affects heart rate variability (HRV). The mediating effect of mental and physical health factors on the relationship between CRTI, its severity and HRV has not been previously studied and investigated. A cross-sectional mediation analysis of the ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE) prospective cohort study was performed. The sample consisted of injured and uninjured British male servicemen who were frequency-matched based on their age, rank, role-in-theater, and deployment to Afghanistan (2003-2014). CRTI and injury severity (the New Injury Severity Scores [NISS] [NISS < 25 and NISS ≥ 25]) were included as exposure variables. HRV was quantified using the root mean square of successive differences (RMSSD) obtained using pulse waveform analysis. Depression and anxiety mediators were quantified using the Patient Health Questionnaire and Generalized Anxiety Disorder, respectively. Body mass index and the 6-minute walk test (6MWT) represented physical health measures. Two mediation pathways between exposure and outcome variables were examined in comparison with the uninjured group using structural equation modeling. Of 862 servicemen, 428 were injured and 434 were uninjured with the mean age at assessment of 33.9 ± 5.4 (range 23-59) years. Structural equation modeling revealed that depression, anxiety, and body mass index did not significantly mediate the relationship between injury/injury severity and RMSSD. However, the 6MWT significantly mediated the relationship between CRTI and RMSSD (27% mediation). The indirect effect of 6MWT on the relationship between injury severity (NISS ≥ 25 vs. uninjured) and RMSSD was -0.06 (95% CI: -0.12, -0.00, P < .05). The findings suggest that greater physical function may improve HRV following CRTI. Longitudinal studies are warranted to further validate these findings.

Interleukin 6 (IL-6) Regulates GABAA Receptors in the Dorsomedial Hypothalamus Nucleus (DMH) through Activation of the JAK/STAT Pathway to Affect Heart Rate Variability in Stressed Rats.

The dorsomedial hypothalamus nucleus (DMH) is an important component of the autonomic nervous system and plays a critical role in regulating the sympathetic outputs of the heart. Stress alters the neuronal activity of the DMH, affecting sympathetic outputs and triggering heart rate variability. However, the specific molecular mechanisms behind stress leading to abnormal DMH neuronal activity have still not been fully elucidated. Therefore, in the present study, we successfully constructed a stressed rat model and used it to investigate the potential molecular mechanisms by which IL-6 regulates GABAA receptors in the DMH through activation of the JAK/STAT pathway and thus affects heart rate variability in rats. By detecting the c-Fos expression of neurons in the DMH and electrocardiogram (ECG) changes in rats, we clarified the relationship between abnormal DMH neuronal activity and heart rate variability in stressed rats. Then, using ELISA, immunohistochemical staining, Western blotting, RT-qPCR, and RNAscope, we further explored the correlation between the IL-6/JAK/STAT signaling pathway and GABAA receptors. The data showed that an increase in IL-6 induced by stress inhibited GABAA receptors in DMH neurons by activating the JAK/STAT signaling pathway, while specific inhibition of the JAK/STAT signaling pathway using AG490 obviously reduced DMH neuronal activity and improved heart rate variability in rats. These findings suggest that IL-6 regulates the expression of GABAA receptors via the activation of the JAK/STAT pathway in the DMH, which may be an important cause of heart rate variability in stressed rats.

Effects of virtual music therapy on Burnout Syndrome in health workers in Tertiary Hospitals

Background: Health workers are vulnerable to experiencing psychological and physiological stress, including burnout syndrome (BOS). BOS can be measured using the Maslach Burnout Inventory (MBI) assessment. BOS can also affect heart rate variability (HRV). Music therapy is one of the BOS therapies in the recovery phase. This study aims to evaluate the effects of virtual music therapy on "Burnout Syndrome" in health workers in Tertiary Hospitals Methods: This research is a qualitative study and a randomized control trial using a pre-and post-test control group study design on healthcare workers at Dr. Kariadi Hospital and Dr. Cipto Mangunkusumo Hospital for three months. Subjects were divided into two groups, namely the intervention group and the control group, each consisting of 20 people. The instruments used were the MBI-HSS questionnaire and heart rate variability measuring devices for the pretest and posttest. Depending on the data distribution analysis performed using the Shapiro-Wilk test, data analysis was performed using either the Mann-Whitney test or the independent T-test. Data were analyzed using SPSS version 21.0 for Windows. Results: This study shows significant differences in the MBI-HSS scores between the intervention and control groups (p&lt;0.05). In the HRV-SDNN scores, there were only significant differences in the control group (p&lt;0.05), although there was an increase in the mean values in the intervention group. Conclusion: The use of music therapy according to culture and individual preferences can significantly affect the MBI-HSS score, which indicates burnout and increases the HRV value.

Modulation of Heart Rate Variability in Stressed Medical Students Via Breathing Exercise

Background: Stress in medical students is a global concern. Stress disturbs the sympathovagal balance and affects heart rate variability, a sign of healthy cardiovascular homeostasis. Various strategies have been used globally to combat stress and its effects. Aim: To determine how blowing balloon exercise modulatesheart rate variability (HRV) in stressed medical students. Methodology: A pretest-posttest quasi-experimental study wasconducted among stressed medical students at Islamic international medical college Rawalpindi Pakistan. Sixty students diagnosed with moderate stress were enrolled based on Depression Anxiety Stress Scale (DASS) Proforma. The study population was selected by simple random sampling via the balloting method among the stressed medical students. Study participants underwent a supervised blowing balloon exercise.Before and after a supervised blowing balloon exercise, the participants' pulmonary function tests, electrocardiograms, and DASS scores were measured. Participants' ECGs and pulmonary function tests were recorded viaPower lab (A.D. Instruments, model yam 4/25T, South Wales, Australia). Results: Blowing balloon exercise resulted in a significant reduction of DASS score (p&lt;0.001) and significant improvement in pulmonary function tests (p&lt;0.001). Among Heart rate variability parameters, the participants' standard deviation of successive N-N intervals, high-frequency components, and high-frequency normalized units significantly increased (p&lt;0.05) after blowing balloon exercise. Heart rate, low-frequency normalized units, and the ratio of low-frequency normalized value to high-frequency normalized value were significantly reduced (p&lt;0.05) after blowing balloon exercise. Conclusions: Blowing balloon exercise enhances medical students' heart rate variability and pulmonary function tests while reducing their stress levels. This cost-effective and easy exercise can be performed by stressed students without any time or place barrier. Keywords: Anxiety, Breathing Exercise, Depression, Heart Rate Variability, Stress, Sympathovagal Balance.

Relationship of vitamin B12, folic acid and homocysteine level with time domain measures of heart rate variability in female Metabolic Syndrome

Background: Metabolic syndrome (MetS) is a major risk factor for cardiac mortality and morbidity. Hyperhomocysteinemia and folic acid are related with MetS. Both MetS and hyperhomocysteinemia adversely affect heart rate variability (HRV). Objectives: To assess the relationship of vitamin B12, folic acid and homocysteine levels with HRV in female MetS patients. Methods: This cross sectional study was carried out on 40 female MetS patients of 25-45 years of age. Forty apparently healthy female with similar age were control. Chemiluminescent immunoassay measured serum vitamin B12, folic acid, homocysteine level and time domain parameters of HRV were recorded by Powerlab 8/35, AD instruments, Australia. Independent sample ‘t’ test and pearson correlation coefficient test was used for statistical analysis Results: In this study, all the time domain HRV variables ( Standard deviation of all RR intervals-SDRR, Coefficient variation of RR interval-CVRR, The square root of mean squared difference of RR intervals-RMSSD and Number of R-R interval differing &gt;50ms from adjacent intervals divided by the total number of all R-R intervals-pRR50%) were significantly lower (p&lt;0.05) in MetS patients compared to control. But correlation analysis showed only the folic acid level was significantly negatively correlated (p&lt;0.05) with SDRR, CVRR, RMSSD and pRR50%. Conclusion: The result of this study showed inverse relation of low HRV with low serum folic acid levels in female MetS patients. J Bangladesh Soc Physiol. 2022, June; 17(1): 41-48

Electromagnetic Fields as a Health Risk Factor

This study is a collection of findings of published articles from the Department of Medical Biophysics and Department of Public Health at the Jessenius Faculty of Medicine in Martin, Comenius University Bratislava (JFM CU) with the topic on epidemiology of electromagnetic fields. During 14 years, 13 principal publications were created, of which 11 studies deal with radio frequency signals from mobile phones (mainly GSM900 and GSM1800 standard); one study describes the construction of a new exposure system and the other deals with the effects of low frequency electromagnetic fields. The results showed that the electromagnetic fields can affect heart rate variability both in humans and animals; increasing the activity of the parasympathetic or sympathetic nerve systems depending on place of body exposure (head or thorax, respectively); may cause disorders of heart rhythm; loss of concentration; headaches; and/or burning sensations in the ear area. Parameters of exposition were compared with the values issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). They had not exceeded the permitted limits. However, compared to data of the Bio Initiative Report, in some cases, our measured values exceeded their limits.

Evaluation of Heart Rate Variability in Children with Congenital Heart Diseases before and after Surgical Repair

Background: Surgical repair of congenital heart diseases (CHD) affects heart rate variability (HRV) in different ways. It leads to varying degrees of cardiac autonomic derangement, clinically detectable as depression of HRV parameters. The aim of this work was to evaluate HRV in children with CHDs before and after surgical repair to detect the effect of CHDs (acyanotic or cyanotic) and cardiac surgery on cardiac autonomic function.&#x0D; Methods: This observational case-control study enrolled thirty cases with CHD. Cases were divided in two equal groups: group1 included children with CHDs (not repaired) before surgical intervention and group 2 included children after surgical repair of CHDs. Another fifteen healthy children, matched for age and sex, were enrolled as a control group. All children in this study were subjected to full history taking, clinical evaluation, Holter monitor, twenty-four-hour ambulatory electrocardiographic recordings and the seven time-domain indices of HRV.&#x0D; Results: There was significant increase of HR in patients before surgical repair as compared to patients after surgical repair as compared to control group. There was significant decrease of PNN50, r MMSD, SDNN index and SDANN of children before surgical repair as compared to children after surgical repair as compared to controls. There was a negative significant correlation between HR and age before surgery, after surgery there was a negative significant correlation between HR and age, pNN50, rMMSD, SDNN index and SDANN, in control there was negative significant correlation with age, SDNN index, SDANN and SDNN.&#x0D; Conclusion: HRV parameters increased significantly in children with CHDs after surgical repair as compared to these before surgical repair denoting effect of cardiac surgery on cardiac autonomic function.

Does transcatheter ventricular septal defect closure affect heart rate variability in children?

BackgroundHeart rate variability (HRV) is a sign of the cardiac autonomic nervous system. Its evaluation in pediatric ventricular septal defect (VSD) cases before and after transcatheter closure contributes to an understanding of cardiac autonomic control. MethodsNineteen children with VSDs treated with transcatheter closure and 18 healthy children were enrolled in this study. A 24-h Holter rhythm monitor was applied to all patients before VSD closure and to those in the control group. Holter rhythm monitoring was repeated at three months in the patient group. HRV parameters were measured using the Cardio Scan Premier 12® program. Frequency-domain (total power; very-low-frequency, low-frequency (LF), and high-frequency (HF) indices; and the LF/HF ratio) and time-domain (standard deviation of all RR intervals (SDNN), standard deviation of 5-min averages of RR intervals (SDANN), the SDNN index, percentage of the difference between adjacent RR intervals, and the square root of the mean of the sum of square differences between adjacent filtered RR intervals) parameters were assessed. ResultsBefore the procedure, SDNN, SDANN, and total power values were lower in the patient group than in the control group; other parameters were similar in the two groups. No significant difference in the SDNN, SDANN, or total power was detected between the patient and control groups in the third month, indicating that autonomic control of patients’ hearts became normal during the third postoperative month. No correlation was detected between any hemodynamic parameters and any time-domain or frequency-domain parameters before closure. ConclusionThis study showed that transcatheter closure of VSDs changed HRV parameters in pediatric patients.

Diesel exhaust particles affected heart rate variability but not endothelial function – results from a controlled chamber study

Diesel exhaust particles affected heart rate variability but not endothelial function – results from a controlled chamber study

Central markers of obesity affect heart rate variability independent of physical activity in young adults.

ABSTRACTIntroduction:Obesity is considered to be a risk factor for a variety of cardiovascular conditions. Various markers for obesity are used to evaluate effect of obesity on cardiovascular autonomic activity. In light of conflicting reports on effect of obesity on heart rate variability (HRV), use of obesity indices, and the effect of physical activity on HRV, we evaluated autonomic activity in young Indian obese adults using revised Indian and World Health Organization (WHO) body mass index (BMI) guidelines for obesity, waist circumference (WC), and waist–hip ratio (WHR) taking into consideration the level of physical activity.Methods:The study was conducted on 91 young healthy adults. Height, weight, waist, and hip circumference were recorded to determine BMI and WHR. Five-minute electrocardiogram (ECG) was recorded for assessment of HRV. Physical activity was assessed by the WHO Global Physical Activity Questionnaire (GPAQ).Results:Waist circumference showed a negative correlation with the time domain parameters of HRV and high frequency normalized units (HFnu) while a positive correlation with low frequency normalized units (LFnu). In multiple linear regression analysis, time domain indices, HFnu and total power decreased while LFnu increased with an increase in WC. The result was supported by the similar effect of waist–hip ratio categories on HRV in analysis of covariance (ANCOVA). Physical activity had no effect on HRV.Conclusion:Central obesity parameters are better predictors of effect of obesity on HRV independent of the effect of physical activity.

Effects of Changes in Environmental Color Chroma on Heart Rate Variability and Stress by Gender.

With increasing time spent indoors during the coronavirus disease pandemic, occupants are increasingly affected by indoor space environmental factors. Environmental color stimulates human vision and affects stress levels. This study investigated how changing environmental color chroma affected heart rate variability (HRV) and stress. The HRV of nine males and fifteen females was measured during exposure to 12 color stimuli with changes in chroma under green/blue hues and high/low-value conditions, and a stress assessment was performed. The effect of chroma on the HRV of males and females was verified, but the interaction effect between chroma and gender was not. ln(LF) and RMSSD were valid parameters. ln(LF) of males and females decreased as chroma increased under the green hue and low-value conditions; RMSSD was reduced as chroma increased in the blue hue and low-value conditions. ln(LF) decreased as chroma increased under blue hue and high-value conditions in males. Color–stress evaluation revealed that the higher chroma under high-value conditions, the more positive the stress emotion, and the lower the chroma under low-value conditions, the more negative the stress emotion. As chroma increased under low-value conditions, color is a stress factor; for men, this effect was more evident in the blue hue.

Heart Rate Fragmentation in Patients with Type 2 Diabetes Mellitus

Heart rate fragmentation (HRF) is a recently proposed approach to evaluate ultra‐rapid variability of heart rate. HRF has been shown to be increased in the aging process and in conditions such as coronary artery disease. Moreover, it proved to be a strong biomarker of adverse cardiovascular events, mortality and was an independent predictor of atrial fibrillation. Type 2 diabetes mellitus (DM) is a disease known to affect heart rate variability (HRV) indices markedly; however, HRF in diabetic patients is to be studied. We aimed to evaluate HRF in patients with DM, without autonomic cardiovascular neuropathy, compared to their healthy counterparts. Electrocardiographic (ECG) recordings collected from patients with diabetes (n=102) and healthy subjects (n=96), aged 44 to 59 years, were retrospectively analyzed from the Cardiovascular Physical Therapy Laboratory database. ECG were recorded at rest (supine) for 10 to 15 minutes. RR interval (RRi) series were processed by the customized software PyBios. RRi values were symbolized as “‐1”, “0,” or “1” when the differences between successive RRi were negative, null, or positive, respectively. The percentage of inflection points (PI) was quantified and sequences of 4 consecutive symbols, so‐called “words”, were analyzed computing the occurrence of words with zero (W0), one (W1), two (W2), or three (W3) inflections points. The occurrence of words with only hard (‐1 to 1: WH), soft (‐1 to 0 or 0 to 1: WS), or mixed (WM) (i.e., both H and S) transitions were also quantified. Patients with diabetes presented higher PIP (58±1 vs 56±1, p=0.033), W3(17±1 vs14±1, p&lt;0.001), WS(25±2 vs16±1, p&lt;0.001) and WM(22±1 vs 17±1, p&lt;0.001). On the other hand, patients with diabetes showed a lower percentage of W1 (31±1 vs 35±1, p=0.024) and WH (47±2 vs 61±2, p&lt;0.001). The occurrence of W0 and W2 were similar between groups. In conclusion, diabetics patients without autonomic cardiovascular neuropathy have augmented fragmentation of heart rate as compared to healthy subjects. Clinical applicability: In the future, studies with this approach might be useful to assess heart rate dynamic abnormalities in order to detect cardiac risks in patients with diabetes mellitus.

Cardiac autonomic modulation in children with severe liver disease, before and after liver transplantation.

The cardiovascular system is directly influenced by the autonomic nervous system (ANS); its changes affect heart rate variability (HRV) and are sensitive indicators of physiological changes. Autonomic dysfunction (AD) is manifested in up to 60% of patients with cirrhosis. Therefore, we aim to analyze the indexes of HRV pre- and post-surgery of children submitted for liver transplantation (LT). HRV, in children of both genders from 6 months of age to 10 years, that attended at the pediatric surgery clinic in the queue for LT at the Children's Institute were analyzed. To access HRV we analyzed indexes such as standard deviation of the RR intervals (SDNN), root-mean-square of the successive normal sinus RR interval difference (RMSSD), low frequency (LF), high frequency (HF), and LF/HF. The analysis of the behavior of cardiac autonomic modulation, in the period prior to LT and after surgery, showed an increase in HRV linear parameters SDNN, TINN (triangular interpolation of NN interval histogram), HFms2. In the time domain, there was also an increase in the HFms2 index. The analysis of the period preceding LT and two months after surgery showed an increase in the HRV linear parameters representing a global HRV improvement. In the time domain, there was also an increase in the HFms2 index, parasympathetic tone of the HRV.